This invention relates generally to novel methods, apparatuses, and compositions of matter useful in controlling the growth of organisms within slurry transporting pipelines. As described for example in U.S. Pat. Nos. 8,168,071, 6,586,497, 5,709,731, 4,624,680, 4,546,612, 4,282,006 and 4,206,610, the transport of many slurries (such as ore slurries) is commonly accomplished using mild steel pipelines. Essentially, the ore is grinded and mixed with a fluid like water in order to form a mud that can then be pumped through the pipeline.
As with any system comprising large volumes of water, uncontrolled microbial growth and activity can create severe operational, environmental, and human safety problems in slurry pipelines. Problems caused or intensified by microbial growth and activity includes corrosion, solids production, hydrogen sulfide (H2S) generation, and contamination of the slurry. The microorganisms responsible for these problems can be both aerobic and anaerobic and include oxygen-reducing and sulfate-reducing bacteria. As the slurry water often comprises reservoir or seawater it will typically contain both problematic bacteria as well as required nutrients.
As described in International Patent application WO 1996033296, bacterial corrosion is often caused by sessile anaerobic bacteria living under a thick biofilm composed of aerobic and facultative bacteria enmeshed in a fibrous anionic ion exchange resin that severely limits the penetration of charged molecules. (See Influence of biofilm on efficacy of biocides on corrosion-causing bacteria, by J. W. Costerton, et al, Materials Performance, Vol. 23, No. 2, p. 13, (1984)). Corrosion (pitting) caused by bacteria frequently results in extensive damage. Pipe systems, tank bottoms, and other pieces of equipment can rapidly fail if there are areas where microbial corrosion is occurring.
A number of prior art methods have been proposed for addressing microbiological infestations of pipelines which include: temperature control, metabolite removal, pH control, Eh control, radiation, filtration, salinity control, chemical control (e.g., oxidizers, biocides, acids, alkalis), solids control (e.g., pigging or scraping the internal pipeline), and bacteriological controls (e.g., bacteria phages, enzymes, parasitic bacteria, monoclonal antibodies, competitive microflora). Some of these methods will kill the microorganisms, while others stress or disturb them sufficiently to inhibit their activity. Unfortunately none of these methods present many downsides. Moreover, they are not optimized for the specific conditions and requirements inherent in infestations within slurry transporting pipelines.
Accordingly, there is an ongoing need for a method of reducing microbiological infestations within slurry transporting pipelines. The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “Prior Art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 CFR §1.56(a) exists.